Turbogenerator exhaust silencer

ABSTRACT

An exhaust silencing device and method for silencing a turbogenerator includes a housing, an intake manifold, at least two exhaust outlet ports and flow channels which extend in a bifurcated path from the intake manifold to the exhaust outlet ports and which provide a length to height (or diameter) ratio permitting a compact fluid flow profile.

CROSS REFERENECE TO RELATED APPLICATIONS

[0001] This patent application claims priority under 35 U.S.C. 119 toprovisional application serial No. 60/245,700, filed Nov. 2, 2000, thecontents of which are incorporated herein in their entirety byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to exhaust silencers.More particularly, the invention relates to exhaust silencers for usewith turbogenerator systems.

[0004] 2. Discussion of the Background

[0005] The present inventors recognized that exhaust silencers for usewith turbogenerator systems should be compact, provide a low profile,have a high noise reduction efficiency, include easy installation to aturbogenerator system, and have an aesthetic design which complimentsthe turbogenerator system.

SUMMARY OF THE INVENTION

[0006] The invention provides a novel exhaust silencer device,comprising:

[0007] a housing;

[0008] an intake wall and an exhaust wall disposed within said housingand forming a flow channel;

[0009] an intake manifold formed within said intake wall; and

[0010] at least two exhaust outlet ports formed within said exhaustwall;

[0011] wherein said flow channel extends from said intake manifold andis bifurcated to terminate at said two exhaust outlet ports therebyforming a substantially T-shaped configuration.

[0012] The invention also provides a novel exhaust silencer system,comprising:

[0013] an exhaust silencer device including a housing, an intakemanifold, at least two exhaust outlet ports and a flow channel formed insaid housing, said flow channel extend from said intake manifold to theexhaust outlet ports in a bifurcated configuration; and a turbogeneratorcoupled to said intake manifold, said turbogenerator supplying exhaustto said exhaust silencer device.

[0014] The invention also provides a method for silencing exhaust flowassociated with a turbogenerator, comprising:

[0015] directing exhaust flow into an intake manifold; and directingsaid exhaust flow from said intake manifold to at least two exhaustoutlet ports via a flow channel;

[0016] wherein said exhaust flow is bifurcated between said intakemanifold and said at least two exhaust outlet ports such that saidexhaust flow includes a compact fluid flow profile.

[0017] Additional objects and advantages of the invention will be setforth in the description which folllows, and in part will be evidentfrom the description, or may be learned by practice of the invention.The objects and advantages of the invention may be realized and obtainedby means of the instrumentalities and combinations particularly pointedout hereinafter or by other instrumentalities and combinations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] A more complete appreciation of the invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

[0019]FIG. 1A is perspective view, partially in section, of anintegrated turbogenerator system;

[0020]FIG. 1B is a magnified perspective view, partially in section, ofthe motor/generator portion of the integrated turbogenerator of FIG. 1A;

[0021]FIG. 1C is an end view, from the motor/generator end, of theintegrated turbogenerator of FIG. 1A;

[0022]FIG. 1D is a magnified perspective view, partially in section, ofthe combustor-turbine exhaust portion of the integrated turbogeneratorof FIG. 1A;

[0023]FIG. 1E is a magnified perspective view, partially in section, ofthe compressor-turbine portion of the integrated turbogenerator of FIG.1A;

[0024]FIG. 2 is a block diagram schematic of a turbogenerator systemincluding a power controller having decoupled rotor speed, operatingtemperature, and DC bus voltage control loops;

[0025]FIG. 3A is a perspective view of an exhaust side of aturbogenerator exhaust silencer;

[0026]FIG. 3B is a perspective view of an intake side of theturbogenerator exhaust silencer of FIG. 3A;

[0027]FIG. 4A is a sectional view of FIG. 5 taken along line E-Eillustrating a portion of flow channel without an annual forming inset;

[0028]FIG. 4B is a sectional view of FIG. 5 taken along line E-Eillustrating a portion of a length of an annular shaped flow channel;

[0029]FIG. 5 is a sectional view of FIG. 3A taken along line 5-5illustrating the flow channel;

[0030]FIG. 6 is a sectional view of a prior art turbogenerator exhaustsilencer including an exhaust configuration that extends in-line withexhaust intake; and

[0031]FIG. 7 is a sectional view of a prior art turbogenerator exhaustsilencer including an exhaust configuration with a geometry ofsubstantial bends.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Referring now to the drawings, like reference numerals designateidentical or corresponding parts throughout the several views.

[0033] Mechanical Structural Embodiment of a Turbogenerator

[0034] With reference to FIG. 1A, an integrated turbogenerator 1according to the present invention generally includes motor/generatorsection 10 and compressor-combustor section 30. Compressor-combustorsection 30 includes exterior can 32, compressor 40, combustor 50 andturbine 70. A recuperator 90 may be optionally included.

[0035] Referring now to FIG. 1B and FIG. 1C, in a currently preferredembodiment of the present invention, motor/generator section 10 may be apermanent magnet motor generator having a permanent magnet rotor orsleeve 12. Any other suitable type of motor generator may also be used.Permanent magnet rotor or sleeve 12 may contain a permanent magnet 12M.Permanent magnet rotor or sleeve 12 and the permanent magnet disposedtherein are rotatably supported within permanent magnet motor/generatorstator 14. Preferably, one or more compliant foil, fluid film, radial,or journal bearings 15A and 15B rotatably support permanent magnet rotoror sleeve 12 and the permanent magnet disposed therein. All bearings,thrust, radial or journal bearings, in turbogenerator 1 may be fluidfilm bearings or compliant foil bearings. Motor/generator housing 16encloses stator heat exchanger 17 having a plurality of radiallyextending stator cooling fins 18. Stator cooling fins 18 connect to orform part of stator 14 and extend into annular space 10A betweenmotor/generator housing 16 and stator 14. Wire windings 14W exist onpermanent magnet motor/generator stator 14.

[0036] Referring now to FIG. 1D, combustor 50 may include cylindricalinner wall 52 and cylindrical outer wall 54. Cylindrical outer wall 54may also include air inlets 55. Cylindrical walls 52 and 54 define anannular interior space 50S in combustor 50 defining an axis 51.Combustor 50 includes a generally annular wall 56 further defining oneaxial end of the annular interior space of combustor 50. Associated withcombustor 50 may be one or more fuel injector inlets 58 to accommodatefuel injectors which receive fuel from fuel control element 50P as shownin FIG. 2, and inject fuel or a fuel air mixture to interior of 50Scombustor 50. Inner cylindrical surface 53 is interior to cylindricalinner wall 52 and forms exhaust duct 59 for turbine 70.

[0037] Turbine 70 may include turbine wheel 72. An end of combustor 50opposite annular wall 56 further defines an aperture 71 in turbine 70exposed to turbine wheel 72. Bearing rotor 74 may include a radiallyextending thrust bearing portion, bearing rotor thrust disk 78,constrained by bilateral thrust bearings 78A and 78B. Bearing rotor 74may be rotatably supported by one or more journal bearings 75 withincenter bearing housing 79. Bearing rotor thrust disk 78 at thecompressor end of bearing rotor 76 is rotatably supported preferably bya bilateral thrust bearing 78A and 78B. Journal or radial bearing 75 andthrust bearings 78A and 78B may be fluid film or foil bearings.

[0038] Turbine wheel 72, Bearing rotor 74 and Compressor impeller 42 maybe mechanically constrained by tie bolt 74B, or other suitabletechnique, to rotate when turbine wheel 72 rotates. Mechanical link 76mechanically constrains compressor impeller 42 to permanent magnet rotoror sleeve 12 and the permanent magnet disposed therein causing permanentmagnet rotor or sleeve 12 and the permanent magnet disposed therein torotate when compressor impeller 42 rotates.

[0039] Referring now to FIG. 1E, compressor 40 may include compressorimpeller 42 and compressor impeller housing 44. Recuperator 90 may havean annular shape defined by cylindrical recuperator inner wall 92 andcylindrical recuperator outer wall 94. Recuperator 90 contains internalpassages for gas flow, one set of passages, passages 33 connecting fromcompressor 40 to combustor 50, and one set of passages, passages 97,connecting from turbine exhaust 80 to turbogenerator exhaust output 2.

[0040] Referring again to FIG. 1B and FIG. 1C, in operation, air flowsinto primary inlet 20 and divides into compressor air 22 andmotor/generator cooling air 24. Motor/generator cooling air 24 flowsinto annular space 10A between motor/generator housing 16 and permanentmagnet motor/generator stator 14 along flow path 24A. Heat is exchangedfrom stator cooling fins 18 to generator cooling air 24 in flow path24A, thereby cooling stator cooling fins 18 and stator 14 and formingheated air 24B. Warm stator cooling air 24B exits stator heat exchanger17 into stator cavity 25 where it further divides into stator returncooling air 27 and rotor cooling air 28. Rotor cooling air 28 passesaround stator end 13A and travels along rotor or sleeve 12. Statorreturn cooling air 27 enters one or more cooling ducts 14D and isconducted through stator 14 to provide further cooling. Stator returncooling air 27 and rotor cooling air 28 rejoin in stator cavity 29 andare drawn out of the motor/generator 10 by exhaust fan 11 which isconnected to rotor or sleeve 12 and rotates with rotor or sleeve 12.Exhaust air 27B is conducted away from primary air inlet 20 by duct 10D.

[0041] Referring again to FIG. 1E, compressor 40 receives compressor air22. Compressor impeller 42 compresses compressor air 22 and forcescompressed gas 22C to flow into a set of passages 33 in recuperator 90connecting compressor 40 to combustor 50. In passages 33 in recuperator90, heat is exchanged from walls 98 of recuperator 90 to compressed gas22C. As shown in FIG. 1E, heated compressed gas 22H flows out ofrecuperator 90 to space 35 between cylindrical inner surface 82 ofturbine exhaust 80 and cylindrical outer wall 54 of combustor 50. Heatedcompressed gas 22H may flow into combustor 54 through sidewall ports 55or main inlet 57. Fuel (not shown) may be reacted in combustor 50,converting chemically stored energy to heat. Hot compressed gas 51 incombustor 50 flows through turbine 70 forcing turbine wheel 72 torotate. Movement of surfaces of turbine wheel 72 away from gas moleculespartially cools and decompresses gas 51D moving through turbine 70.Turbine 70 is designed so that exhaust gas 107 flowing from combustor 50through turbine 70 enters cylindrical passage 59. Partially cooled anddecompressed gas in cylindrical passage 59 flows axially in a directionaway from permanent magnet motor/generator section 10, and then radiallyoutward, and then axially in a direction toward permanent magnetmotor/generator section 10 to passages 98 of recuperator 90, asindicated by gas flow arrows 108 and 109 respectively.

[0042] In an alternate embodiment of the present invention, low pressurecatalytic reactor 80A may be included between fuel injector inlets 58and recuperator 90. Low pressure catalytic reactor 80A may includeinternal surfaces (not shown) having catalytic material (e.g., Pd or Pt,not shown) disposed on them. Low pressure catalytic reactor 80A may havea generally annular shape defined by cylindrical inner surface 82 andcylindrical low pressure outer surface 84. Unreacted and incompletelyreacted hydrocarbons in gas in low pressure catalytic reactor 80A reactto convert chemically stored energy into additional heat, and to lowerconcentrations of partial reaction products, such as harmful emissionsincluding nitrous oxides (NOx).

[0043] Gas 110 flows through passages 97 in recuperator 90 connectingfrom turbine exhaust 80 or catalytic reactor 80A to turbogeneratorexhaust output 2, as indicated by gas flow arrow 112, and then exhaustsfrom turbogenerator 1, as indicated by gas flow arrow 113. Gas flowingthrough passages 97 in recuperator 90 connecting from turbine exhaust 80to outside of turbogenerator 1 exchanges heat to walls 98 of recuperator90. Walls 98 of recuperator 90 heated by gas flowing from turbineexhaust 80 exchange heat to gas 22C flowing in recuperator 90 fromcompressor 40 to combustor 50.

[0044] Turbogenerator 1 may also include various electrical sensor andcontrol lines for providing feedback to power controller 201 and forreceiving and implementing control signals as shown in FIG. 2.

[0045] Alternative Mechanical Structural Embodiments of the IntegratedTurbogenerator

[0046] The integrated turbogenerator disclosed above is exemplary.Several alternative structural embodiments are known.

[0047] In one alternative embodiment, air 22 may be replaced by agaseous fuel mixture. In this embodiment, fuel injectors may not benecessary. This embodiment may include an air and fuel mixer upstream ofcompressor 40.

[0048] In another alternative embodiment, fuel may be conducted directlyto compressor 40, for example by a fuel conduit connecting to compressorimpeller housing 44. Fuel and air may be mixed by action of thecompressor impeller 42. In this embodiment, fuel injectors. may not benecessary.

[0049] In another alternative embodiment, combustor 50 may be acatalytic combustor.

[0050] In another alternative embodiment, geometric relationships andstructures of components may differ from those shown in FIG. 1A.Permanent magnet motor/generator section 10 and compressor/combustorsection 30 may have low pressure catalytic reactor 80A outside ofannular recuperator 90, and may have recuperator 90 outside of lowpressure catalytic reactor 80A. Low pressure catalytic reactor 80A maybe disposed at least partially in cylindrical passage 59, or in apassage of any shape confined by an inner wall of combustor 50.Combustor 50 and low pressure catalytic reactor 80A may be substantiallyor completely enclosed with an interior space formed by a generallyannularly shaped recuperator 90, or a recuperator 90 shaped tosubstantially enclose both combustor 50 and low pressure catalyticreactor 80A on all but one face.

[0051] Alternative Use of the Invention Other than in IntegratedTurbogenerators

[0052] An integrated turbogenerator is a turbogenerator in which theturbine, compressor, and generator are all constrained to rotate basedupon rotation of the shaft to which the turbine is connected. Theinvention disclosed herein is preferably but not necessarily used inconnection with a turbogenerator, and preferably but not necessarilyused in connection with an integrated turbogenerator.

[0053] Turbogenerator System Including Controls

[0054] Referring now to FIG. 2, a preferred embodiment is shown in whicha turbogenerator system 200 includes power controller 201 which hasthree substantially decoupled control loops for controlling (1) rotaryspeed, (2) temperature, and (3) DC bus voltage. A more detaileddescription of an appropriate power controller is disclosed in U.S.patent application Ser. No. 09/207,817, filed Dec. 12, 1998 in the namesof Gilbreth, Wacknov and Wall, and assigned to the assignee of thepresent application which is incorporated herein in its entirety by thisreference.

[0055] Referring still to FIG. 2, turbogenerator system 200 includesintegrated turbogenerator 1 and power controller 201. Power controller201 includes three decoupled or independent control loops.

[0056] A first control loop, temperature control loop 228, regulates atemperature related to the desired operating temperature of primarycombustor 50 to a set point, by varying fuel flow from fuel controlelement 50P to primary combustor 50. Temperature controller 228Creceives a temperature set point, T*, from temperature set point source232, and receives a measured temperature from temperature sensor 226Sconnected to measured temperature line 226. Temperature controller 228Cgenerates and transmits over fuel control signal line 230 to fuel pump50P a fuel control signal for controlling the amount of fuel supplied byfuel pump 50P to primary combustor 50 to an amount intended to result ina desired operating temperature in primary combustor 50. Temperaturesensor 226S may directly measure the temperature in primary combustor 50or may measure a temperature of an element or area from which thetemperature in the primary combustor 50 may be inferred.

[0057] A second control loop, speed control loop 216, controls speed ofthe shaft common to the turbine 70, compressor 40, and motor/generator10, hereafter referred to as the common shaft, by varying torque appliedby the motor generator to the common shaft. Torque applied by the motorgenerator to the common shaft depends upon power or current drawn fromor pumped into windings of motor/generator 10. Bi-directional generatorpower converter 202 is controlled by rotor speed controller 216C totransmit power or current in or out of motor/generator 10, as indicatedby bi-directional arrow 242. A sensor in turbogenerator 1 senses therotary speed on the common shaft and transmits that rotary speed signalover measured speed line 220. Rotor speed controller 216 receives therotary speed signal from measured speed line 220 and a rotary speed setpoint signal from a rotary speed set point source 218. Rotary speedcontroller 216C generates and transmits to generator power converter 202a power conversion control signal on line 222 controlling generatorpower converter 202's transfer of power or current between AC lines 203(i.e., from motor/generator 10) and DC bus 204. Rotary speed set pointsource 218 may convert to the rotary speed set point a power set pointP* received from power set point source 224.

[0058] A third control loop, voltage control loop 234, controls busvoltage on DC bus 204 to a set point by transferring power or voltagebetween DC bus 204 and any of (1) Load/Grid 208 and/or (2) energystorage device 210, and/or (3) by transferring power or voltage from DCbus 204 to dynamic brake resistor 214. A sensor measures voltage DC bus204 and transmits a measured voltage signal over measured voltage line236. Bus voltage controller 234C receives the measured voltage signalfrom voltage line 236 and a voltage set point signal V* from voltage setpoint source 238. Bus voltage controller 234C generates and transmitssignals to bi-directional load power converter 206 and bi-directionalbattery power converter 212 controlling their transmission of power orvoltage between DC bus 204, load/grid 208, and energy storage device210, respectively. In addition, bus voltage controller 234 transmits acontrol signal to control connection of dynamic brake resistor 214 to DCbus 204.

[0059] Power controller 201 regulates temperature to a set point byvarying fuel flow, adds or removes power or current to motor/generator10 under control of generator power converter 202 to control rotor speedto a set point as indicated by bi-directional arrow 242, and controlsbus voltage to a set point by (1) applying or removing power from DC bus204 under the control of load power converter 206 as indicated bybi-directional arrow 244, (2) applying or removing power from energystorage device 210 under the control of battery power converter 212, and(3) by removing power from DC bus 204 by modulating the connection ofdynamic brake resistor 214 to DC bus 204.

[0060] Turbogenerator exhaust silencers are generally single path andare controlled by a length to passage height ratio of an exhaust path.The exhaust path extends from an intake manifold to an exhaust outletport. A large length to diameter (L/D) ratio provides a low and compactfluid profile. A substantially C-shaped, exhaust path allows exhaustflow to move in one direction and curve back in an opposite seconddirection. An exhaust path with substantial bends causes undesired backpressure problems with the exhaust flow.

[0061] Referring now to FIGS. 3A, 3B, and 5, they illustrate oneembodiment of an exhaust silencer system 300 of the present invention.Exhaust silencer system 300 includes housing 302, intake manifold 303,first exhaust outlet port 304 and second exhaust outlet port 306.

[0062] Housing 302 includes top wall 308, bottom wall 310, first sidewall 312, second side wall 314, exhaust wall 316 and intake wall 318.

[0063] Referring to FIG. 5, a sound attenuating material 315 is coupledto exhaust wall 316 and intake wall 318. However, it should beappreciated that sound attenuating material may be positioned anywherewithin or around housing 302 in an appropriate configuration. Twoexemplary sound attenuating materials are fiberglass and mineral woolalso ceramic wool or any other fiberous bulk material used for acousticdamping purposes. Sound attenuating material may be woven, formed asblankets or blown into the exhaust silence system 300.

[0064] Exhaust wall 316 and intake wall 318 are sized and shaped todefine a bifurcated cavity which forms ducting or flow channels 320,322. Flow channels 320, 322 are each continuous from exhaust wall 316 tointake wall 318. Flow channels 320, 322 extend from intake manifold 303,and terminate at first exhaust outlet port 304 and second exhaust outletport 306 which are formed as elbow shaped portions. Intake manifold 303is sized and shaped for coupling to an exhaust of a turbogenerator.

[0065] Intake wall 318 and flow channels 320, 322 form a substantially“T-shaped” configuration through which fluid flows. For example, the“T-shaped” configuration permits flow channels 320, 322 to extend fromintake manifold 303 in a substantially orthogonal direction from centeraxis B-B (FIG. 5) of intake manifold 303 such that fluid enters intakemanifold 303 and is directed outward to first exhaust outlet port 304and second exhaust outlet port 306. Exhaust outlet ports 304, 306 arespaced apart by an “effective length” indicated by two headed arrows online E-E.

[0066] Exhaust silencer 300 may also include turning vanes 332, 334, 336and 338. Turning vanes 332, 338 reduce pressure losses in the elbowbends near first exhaust outlet port 304 and second exhaust outlet port306. Turning vanes 334, 336 reduce the pressure losses at the flowsplitter 324.

[0067] Exhaust silencer 300 may also include annular forming insets 452a, 452 b. However, it should be appreciated that insets may be anyappropriate shape that compliments the flow channels.

[0068] First exhaust outlet port 304 and second exhaust outlet port 306may have any appropriate covering 314 through which the fluid can flow.One exemplary covering 314 is a screen material that filters the fluidflow. Covering 314 prevents debris from collecting in the silencer andsmall animals such as birds and rodents from nesting within.

[0069] Exhaust flow is directed through bifurcated flow channels 320,322 which provide an “effective length”, indicated by two-headed arrowson line E-E. The effective length is the total length which is treatedwith acoustic material and through which exhaust flows from the intaketo the outlet. The effective length may be a length from the intake tothe outlet in the exhaust silencer. Effective lengths useful for thisinvention are between about 2 and 10 centimeters.

[0070] In a configuration of bifurcated flow channels, although the flowis divided, the “effective length” is the total length through whichfluid flows. Therefore, the “effective length” indicated by two-headedarrows on line E-E provides a length of a magnitude comparable to thesubstantially straight exhaust silencer configuration having a flow pathof length E-E. The bifurcation of the flow channel into paths 318-320,and 318-322, minimize profile problems for a given effective length.

[0071] Modifying the configuration of the effective length changes thefluid flow profile. Accordingly, particular configurations or geometriesmay be selected based on desired fluid flow characteristics. Thesubstantially “T-shaped” configuration of flow channels 320, 322 resultsin a fluid profile of silencer system 300 that is low and compact.Additionally, the bifurcation of the exhaust flow into the flow channels320, 322 creates a predetermined L/H ratio a minimal length extending inan outwardly direction from the intake manifold. The flow channels 320,322 need not be exactly T-shaped. There may be same degree of anglebetween flow channels 320, 322 that results in a “Y-shape.” The shape ofthe angle between the flow channels 320, 322 is 180° in the “T-shape”and less than 180° in the “Y-shape.” Shape angles greater than 140° arepreferred, and angles greater than 160° are more preferred. Flowchannels angles are also selected to minimize drain water flow into theengine and direct water to gutters 340 a, 340 b.

[0072] The exhaust flow path is three-dimensional and has a crosssectional area. A minimum cross sectional area is necessary to minimizepressure losses in the exhaust ducting. A larger cross sectional area ofthe ducting reduces the average velocity in the exhaust flow path, andtherefore reduces the pressure losses which are generally a function ofvelocity squared. Exemplary cross sections include, but are not limitedto, a rectangular cross-section, a circular cross section, or an annularcross section.

[0073] Referring now to FIG. 4A, it illustrates a sectional view of oneportion of a bifurcated passage including an exhaust path 400 withtreatment 410. The exhaust flow is directed along the path in adirection shown by arrow F. The rectangular cross section (not shown)has the dimensions of a height H and a width W and an area representedby the H multiplied by W. The area of a circular ducting (not shown) isa function of its diameter. A portion of the effective length isindicated by two-headed arrows on line E.

[0074] Referring now to FIG. 4B, it illustrates a sectional view of oneportion of a bifurcated passage including an exhaust flow path 450 withannular forming inset 452 and acoustic treatment material 454. Theexhaust path flow begins with a diameter indicated by two-headed arrowD2 and continues to annular inset 452 with a diameter D1. Annularforming inset 452 may be made of an acoustic treatment material or anyother appropriate material. Annular forming inset 452 forms a dualpathway 454, 456 for exhaust flow. The exhaust flow is directed alongthe path in a direction shown by arrow F. The cross sectional area (notshown) is based on the diameter. A portion of the effective length isindicated by two-headed arrows on line G.

[0075] Referring again to FIG. 5, the bifurcation of the exhaust flowpermits a reduction in the height H for a rectangular cross section orin the diameter D for a circular cross section of the silencer to yielda lower profile. Bifurcating the exhaust results in about a half of theflow directed into each path 318-320 and 318-322. Thus, the averagevelocity of the fluid in each duct having a height of about ½ the heightof an unbifurcated path, is comparably similar to the average velocityin the unbifurcated path.

[0076] Exhaust silencer 300 minimizes acoustic vibrations because thelength, L, relative to the diameter D for circular ducts, the height Hfor annular ducts, and the smaller of height H and width W forrectangular ducts, is compared to the effective length. The height (H)of the exhaust channels 304, 306 (or at least the length in onedimension thereof for noncircular cross sections) are sized depending onthe length (L) of exhaust channels, such that a high L/H ratio results.The L/H ratio is predetermined for the exhaust channels. For arectangular or annular duct, L/H is used. For a circular silencer duct,L/D is used. The ratio of L/H (or L/D) may be used to determine theacoustic performance of the silencer. The ratio can range from 1 to 20depending on the noise reduction goals for the silencer. One exemplaryL/D ratio is 5. One preferred range is 7-10.

[0077] The depths of first exhaust outlet port 304 and second exhaustoutlet port 306 are also selected to improve the low frequencycharacteristics of the exhaust silencer and optimize for spectralacoustic characteristics of the turbogenerator exhaust system. The depthof the exhaust port is the length from the aperture of, e.g., exhaustoutlet port 304 to the intersection with flow channel 322 which forms aelbow shaped bend.

[0078] Referring to FIG. 6, it illustrates a prior art exhaust silencerconfiguration 600 in which a substantially straight exhaust path extendsan “outward length” from exhaust outlet port 604 along axis C-C. Exhaustflow directed in this manner will result in undesired profile problems.

[0079] Referring to FIG. 7, it illustrates a prior art exhaust silencerconfiguration 700 in which substantially curved exhaust path 702 extendsfrom exhaust outlet port 704. Exhaust flow directed in this manner willresult in undesired backpressure problems.

[0080] Comparatively, bifurcating the exhaust flow path into flow paths320 and 322 doubles the “effective length” without requiring excessivebends that elevate backpressure to an undesirable magnitude.

[0081] Referring again to FIG. 5, it illustrates the bifurcated exhaustflow directed via flow channels 320, 322, which provides improvedacoustic damping efficiency. Although a substantially “T-shaped”configuration is shown, it should be appreciated that any suitablebifurcated configuration may be selected which provides a low andcompact flow.

[0082] Numerous modifications and variations of the present inventionare possible in light of the above teachings. Therefore, the inventionin its broader aspects is not limited to the specific details andrepresentative embodiments shown and described herein. Accordingly,various modifications may be made without departing from the spirit andscope of the general inventive concept as defined by the appended claimsand their equivalent.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. An exhaust silencer device, comprising: ahousing; an intake wall and an exhaust wall disposed within saidhousing, said intake wall and said exhaust wall and forming a flowchannel; an intake manifold formed within said intake wall; at least twoexhaust outlet ports formed within said exhaust wall; and wherein saidflow channel extends from said intake manifold, said flow channel isbifurcated to terminate at said two exhaust outlet ports.
 2. The exhaustsilencer device of claim 1, wherein said flow channel is formed as asubstantially T-shaped configuration.
 3. The exhaust silencer device ofclaim 1, wherein said flow channel has a length to height ratio thatresults in a compact fluid flow profile.
 4. The exhaust silencer deviceof claim 1, wherein sound attenuating material is disposed within saidhousing.
 5. The exhaust silencer device of claim 4, wherein said soundattenuating material is selected from the group consisting offiberglass, mineral wool and ceramic wool.
 6. The exhaust silencer ofclaim 4, wherein said sound attenuating material is a fiberous bulkmaterial.
 7. The exhaust silencer device of claim 4, wherein the soundattenuating material is in a form selected from the group consisting ofwoven material, blankets and blown material.
 8. The exhaust silencer ofclaim 1, wherein said flow channel has a length to height ratio betweenabout 1 to about
 20. 9. The exhaust silencer of claim 1, wherein saidbifurcation delivers a shape angle of at least 140°.
 10. An exhaustsilencer system, comprising: an exhaust silencer device including ahousing, an intake manifold, at least two exhaust outlet ports and aflow channel formed in said housing, said flow channel extend from saidintake manifold to the exhaust outlet ports in a bifurcatedconfiguration; and a turbogenerator coupled to said intake manifold,said turbogenerator supplying exhaust to said exhaust silencer device.11. The exhaust silencer system of claim 10, wherein said bifurcatedconfiguration is substantially T-shaped.
 12. The exhaust silencer systemof claim 10, wherein the diameter of said flow channel are based on thelength such that a compact fluid flow profile is formed.
 13. The exhaustsilencer system of claim 10, wherein said flow channel has a length toheight ratio from about 1 to about
 20. 14. The exhaust silencer systemof claim 10, wherein sound attenuating material is disposed within saidhousing.
 15. The exhaust silencer system of claim 14, wherein said soundattenuating material is selected from the group consisting offiberglass, mineral wool and ceramic wool.
 16. The exhaust silencersystem of claim 14, wherein the sound attenuating material is in a formselected form the group consisting of woven material, blankets and blownmaterial.
 17. A method for silencing exhaust flow associated with aturbo generator, comprising: directing exhaust flow into an intakemanifold; and directing said exhaust flow from said intake manifold toat least two exhaust outlet ports via a flow channel; wherein saidexhaust flow is bifurcated between said intake manifold and said atleast two exhaust outlet ports such that said exhaust flow includes acompact fluid flow profile.
 18. The method of claim 15, wherein thebifurcated flow forms a shape angle of at least 140°.
 19. The method ofclaim 15, wherein said flow channel has a length to height ratio ofbetween about 1 and about
 20. 20. The method of claim 15, wherein saidflow channel has a length to diameter ratio of between about 1 and about20.